<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
    <button id="begin">开始</button>
    <button id="end">结束</button>
    <h1 id="txt">开始抽奖</h1>
<script>
    var tag=document.getElementById('begin');
    var tag=document.getElementById('end')
    var tag=document.getElementById('txt');
    var timer;
    var list=['JJ','俊杰','陈俊杰','CJJ','DJJ']
    console.log(list[0]);
    console.log(list.length);
    begin.onclick=function(){
        clearInterval(timer);
        timer=setInterval(function(){
            var n=parseInt(Math.random()*list.length);
            tag.innerHTML=list[n]
        },100)
    end.onclick=function(){
        clearInterval(timer);
    }
    }
</script>
</body>
</html>